Question

Bitter cassava is often preferred as a crop over sweet cassava because it produces higher yields (more pounds of cassava per hectare planted) in the presence of herbivores. Which of the statements poses a hypothetical relationship?
A. Plants produce chemicals to deter herbivores. Bitter cassava stores toxic compounds in its roots. Because they are below ground, the roots are not eaten and the presence of toxic compounds does not contribute to higher yields.
B. Plants produce chemicals to deter herbivores. Bitter cassava expends energy producing toxic compounds. The more toxic compounds a plant produces, the lower its yields.
C. Plants produce chemicals to deter herbivores. Bitter cassava stores toxic compounds in its tissues. Bitter cassava should incur less damage, and therefore have higher yields.
D. Plants produce chemicals to deter herbivores. Bitter cassava requires additional nitrogen to make these compounds. The additional nitrogen that is used reduces the amount of nitrogen available for plant growth and decreases yields.

Answer 1

Answer:

C. Plants produce chemicals to deter herbivores. Bitter cassava stores toxic compounds in its tissues. Bitter cassava should incur less damage, and therefore have higher yields.

Explanation:

It has been observed that one way certain plants prevents herbivory is secretion of toxic substances. This is the case of Bitter cassava which stores toxic substances in its tissues. These toxic substances help deter herbivores i.e. they discourage herbivores from feeding on the plant (bitter cassava).

Since herbivores which would normally feed on plants, cannot feed on bitter cassava plant specifically due to the poisonous substances in its tissues, the damage of the plant due to herbivory is brought to the minimum. A reduced damage of crops means an increased yield of that crop in terms of pounds of cassava per hectare planted. This is why the bitter cassava yields more than the sweet counterpart of the plant.

Answer 2

Answer:

C. Plants produce chemicals to deter herbivores. Bitter cassava stores toxic compounds in its tissues. Bitter cassava should incur less damage, and therefore have higher yields.

Explanation:

Bitter cassava are able to produce higher yield because they are less disturbed by herbivores due to the production of herbivore-deterring chemicals in their tissues, especially the tissues that are above the ground.

Sweet cassava that is not able to produce the herbivores-deterring chemicals incur damages to its tissues. These damages affect the physiological functions of the plant and thus leads to reduced yield.

Options A is incorrect because herbivores can only get to above the ground tissues.

Option B and D are factually incorrect.

The correct option is C.